The development of society informatization makes it possible to communicate at any place and at any time, and the extensive use of a variety of types of communication devices (e.g. mobile phone, Bluetooth headset, and stereo headphone) and communication technologies not only brings a lot of convenience to our life but also greatly improve our working efficiency. However, meantime it also brings about a severe problem of noises. The communication conducted in noisy environment is hard to be heard clearly and understood, and if the decibels of noises reach a certain degree, communication can not be made, and even worse, the hearing and the physical and psychological health of people are probably injured.
To deal with the problem of noises, some existing earphones are designed with a noise reduction function. These earphones denoise ambient sounds when their noise reduction function is activated and then output noise-reduced sound to the user through earphone loudspeaker(s).
However, ambient noises are variable, the energy grade and the spectrum distribution of ambient noises change with time and place, existing noise-reducing earphones only provide noise reduction activation function and noise reduction deactivation function for the user to deal with noises, such simple selection of either a noise reduction activation function or a noise reduction deactivation function makes it impossible to become user-friendly.
For example, in an environment such as an ordinary office, when the noise reduction function of an earphone is directly activated to reduce noises by more than 25 dB, the user will feel like to be in a depressing professional anechoic room, but due to the existence of ambient noises in this environment, the user cannot just turn off the noise reduction deactivation function.